Causes, incidence, and risk factors

Facioscapulohumeral muscular dystrophy is a genetic disorder. It appears in both men and women and may develop in a child if either parent carries the gene for the disorder. In 10 to 30% of cases, the parents do not carry the genes.

Facioscapulohumeral muscular dystrophy affects about 5 out of 100,000 people. It affects men and women equally.

Symptoms

Men often have more symptoms than women.

Facioscapulohumeral muscular dystrophy mainly affects the face, shoulder, and upper arm muscles. However, it can also affect muscles around the pelvis, hips, and lower leg.

Symptoms can appear after birth, but often they do not appear until age 10 - 26. However, it is not uncommon for symptoms to appear much later in life. In some cases, symptoms never develop.

Symptoms are usually mild and very slowly become worse. Muscle weakness of the face is common, and may include:

Shoulder muscle weakness causes deformities such as pronounced shoulder blades (scapular winging) and sloping shoulders. The person has difficulty raising the arms because of shoulder and arm muscle weakness.

Weakness of the lower legs is possible as the disorder gets worse. The weakness can be severe enough to interfere with walking. A small percentage of people become wheelchair-bound.

Hearing loss and abnormal heart rhythms may occur, but are rare.

Signs and tests

A physical examination will show weakness of the face and shoulder muscles. High blood pressure may be noted but is usually mild. An eye exam may show changes in the blood vessels in the back of the eye.

Treatment

There is no known cure for facioscapulohumeral muscular dystrophy. Treatments are given to control symptoms and improve quality of life. Activity is encouraged. Inactivity such as bedrest can make the muscle disease worse.